Method of and apparatus for automatically controlling the amount of heat supplied to alpha building



Oct. 3, 1933. E. c. WEBB 1,929,182

' METHOD OF AND APPARATUS FOR AUTOMATICALLY CONTROLLING THE. AMOUNT OF HEAT SUPPLIED TO A BUILDING Filed April 9, 1932 2 Sheets-Sheet l ENTER E.C.WE'IBB fl TTURNE-s Oct'. 3, 1933. c WEBB 1,929,182

METHOD OF AND APPARATUS FOR AUTOMATICALLY CONTROLLING THE AMOUNT OF HEAT SUPPLIED TO A BUILDING Filed April 9, 1932 2 Sheets-Sheet 2 FIT Z L I 7 4e //\/A/E/y7-U/= E. c. WEBB ml/ M- Patented Oct. 3, 1933 UNITED STATES METHOD OF AND APPARATUS FOR AUTO- MATICALLY CONTROLLING THE AMOUNT OF HEAT SUPPLIED TO A BUILDING Ernest C. Webb, Portland, 0reg., assignor to Iron Fireman Manufacturing Company, Portland,

Oreg.

Application April 9, 1932. Serial No. 604,259

2 Claims.

This invention relates generally to heating systems, and particularly to a method of and apparatus for automatically controlling the amount of heat supplied to a building.

The main object of this invention is to so correlate the action of the heat generating device with reference to the indoor and outdoor temperatures that an ideal condition of uniform and economic heating may be brought about.

The second object is to make it possible to vary the number of times heat is turned on in a given space of time and to utilize the outside temperature changes for the purpose of determining the lengths of the various firing operations.

These, and other objects, will become more apparent from the specification following as illustrated in the accompanying drawings, in which:

Fig. 1 is a somewhat diagrammatic view showing a simple form of dual control as applied to the ordinary warm air furnace.

Fig. 2 is a longitudinal section through the out-- side control element.

Fig. 3 is a plan of Fig. 2 with the casing broken away in section.

Fig. 4 is a section taken along the line 4-4 in Fig. 2.

Fig. 5 is a section taken along the line 5-5 in Fig. 2.

Similar numbers of reference refer to similar parts throughout the several views.

Before entering into a detailed description of this invention a brief review will be given of the common forms of controls, the objections thereto and the outstanding differences between my method of control and those now in use.

It is now the common practice to control the action of a heat generating device by circuit-controlling elements, either temperature or pressure actuated, and located either at the source of generation or the point of delivery, or both the point of generation and the point of delivery. Owing to the fact that the heat generated is transferred to air or water and that the type of generating device varies from gaseous to liquid and solid fuels there are a great many varieties of combinations of controls, but in the main, and with only a few exceptions, all of these control the generation of heat in accord with conditions prevailing at the furnace where the heat is generated, or in the room where the heat is delivered.

Such systems, while vastly superior to manual controls, have many drawbacks among which is the fact that when a stoker or other device is controlled by a room temperature the decline in.

temperature which can take place after the stoker has been turned on and before it can generate the desired supply of heat to overcome this decline, is so great in most instances as to be objectionably noticeable. This is particularly true 0 with steam and hot water installations.

With my method the control problem is approached in a different manner, namely the stoker may be stopped either by a maximum room or furnace temperature or boiler pressure, 5 but it will be operated periodically at variable frequencies, which may be determined manually. and the length of the period of each operation is controlled thermostatically by outside temperatures. In other words, the necessary equipment consists of means for controlling the fre quency or number of times per day heat is applied to a building (this may be fixed or adjustable depending upon the application), and there is also employed a means for automatically con trolling the duration of time this heat is applied, depending upon the outside temperature, that is the temperature surrounding the building. For example, a given application may require -for the proper heating of a building heat applied fifty percent of the time at fifty degrees outside temperature and seventy-five percent of the time at twenty degrees outside temperature.

Regardless of the outside temperature the heat will be turned on a predetermined number 35 of times each day-for example, three times per hour. However, the length of time it would remain on each period is determined by the outside temperature. In this case at fifty degrees outside temperature it would remain on fifty percent of one-third of an hour, or ten minutes. While at twenty degrees outside temperature it would remain on seventy-five percent of one-third of an hour, or fifteen minutes.

It will be understood that in speaking of turning on heat reference is made to opening a valve on a furnace or boiler, opening a steam or hot water valve, starting an oil or gas burner, turning a switch on an electric heater, or starting a stoker or similar apparatus.

Since there are many ways in which the me chanical details of this system could be worked out only representative forms will be illustrated and described herein in which a stoker and warm air installation is considered throughout.

Referring particularly to the drawings, there is shown a stoker 10 by means of which fuel is fed through a duct 11 into a retort 12. A fan 13 supplies air to the combustion and the rate at which fuel is fed to the combustion is deter- 1H mined by a change gear, under the control of the hand wheel 14. The stoker contains the usual means for controlling the volume of air delivered thereto and other common accessories well understood in the art.

The stoker motor is controlled by a furnace thermostat 16 which is mounted on the warm air furnace 17. The thermostat 16 is of the twoway type having a neutral wire 18, a motor starting wire 19 and a motor stopping wire 20 which are connected to the motor switch 21, which switch determines whether or not current can flow from the power line 22 to the motor circuit 23.

Although this is a common form of control it is briefly stated that should the temperature of the furnace 1'2 rise above a predetermined maximum, the thermostat 16 will close the circuit between the wires 18 and 20 causing the motor switch 21 to open and stop the motor 15, while a drop in the furnace temperature below a predetermined minimum will close the circuit through thewires 18 and 19 causing the switch 21 to close the motor circuit.

The mechanism thus far described is in common use.

In Fig. 1 there is illustrated the addition of a time contacting device illustrated'in detail in Figs. 2 to 5. This device consists of a cam 24 which is continuously operated by a motor 25 which operates directly from the power line 22. The cam 24 is provided with a raised portion 26 and a low portion 27. The surfaces 26 and 2'7 are in line with a bimetallic element 28 which is long enough to permit a considerable movement at the end 29, and flexible enough to take the deflection from the low point to the high point of the cam without taking a permanent setting.

The cam 24 is driven at a constant rate of speed, for example about three RVP. H., which rate may be varied by shifting the positionof a friction pinion 30 between the friction disks 31 and 32, the former being on the shaft of the motor 25 and the latter on the shaft 33 which carries a worm 34 which, in turn, meshes with a worm wheel 35 on the cam shaft 36. The friction pinion 30 is carried on a slidable bracket 37 whose position may be controlled by the screws 38 operating in the slots 39.

The element 28 is supported by an insulated bracket 40 which is adjustably mounted on the pivot 41 under the control of the screws 42. The element 28 is connected by means of the wire 43 to the motor starting wire 19. The wire 19 when used with my device is provided with a manually operated switch 44 which is normally open. On the side of the switch 44 opposite the connection of the wire 43 is joined a wire 45 which runs to a brush 46 riding on the side of the cam 24.

It will be observed that the time contacting mechanism is all confined within a casing 47 which is outside of the wall 48 and is subjected to what I shall refer to as outside temperature.

The operation of the form of the device shown in Fig. 1 is as follows: Assuming that the operation of the stoker is normally controlled by the furnace thermostat 16that is, that it will be shut off whenever the furnace temperature rises above a predetermined maximum by the closing of the circuit through the wires 18 and 20, and then remembering that the cam 24 is continuously operating in order to intermittently close the circuit around the switch 44, which is normally open, and again remembering that the frequency of operation is controlled by the setting of the pinion 30 and that the length of each period of operation is controlled by the outside temperature and the setting of the element 28, it will be perceived that an ideal condition is now brought about, namely that the character of the stoker operations will be controlled by the outside temperatures under which the stoker is operating, rather than by the desired temperatures at the point or" delivery alone or in conjunction with the limiting temperatures at the point of generation.

It is a well known fact that systems are now in use in which heat regulation is accomplished by correlating outside temperatures with an indoor temperature at some selected point of delivery, for example at a given radiator, and these systems are quite satisfactory under certain conditions, although they cannot be said to be satisfactory under the wide range of conditions commonly encountered in present-day heating problems. This is due to the difiiculty of selecting a representative radiator and the impossibility of maintaining anything like a uniform relationship betweenthe operating conditions of the various radiators in the building. Owing to the fact that such systems are responsive to a drop in temperature at a given point of delivery they naturally operate at a relatively low differential in temperatures. Whereas in my system if the outside temperature is low enough to cause a contact through the thermostat 28 thereby causing a closing operation of the motor switch 21, it will continue to operate until it is stopped by a maximum temperature at the furnace thermostat or pressure regulator 16.

In other words, my system operates at a relatively high differential of temperature or pressure, thereby insuring that all of the radiators will be adequately supplied with heat in increasing proportions as the outside temperature falls, instead of merely causing the generation of enough heat to satisfy the requirements of the individual radiator in spite of the fact that there may be marked deficiencies in the supply at all of the other radiators in the system.

I am aware that certain systems have been evolved utilizing changes in outside temperatures for the purpose of controlling heat generating devices, I therefore do not claim this feature broadly but I do intend to cover all such forms and modifications thereof as fall fairly within the appended claims.

I claim:

1. A control mechanism for heat generating devices consisting of a continuously operated cam, a resilient bimetallic brush adapted to engage the high portion of said cam as it rotates, means for varying the degree of contact between said brush and cam, and means for varying the speed of rotation of said cam.

2. A control mechanism for heat generating devices consisting of a continuously operated cam, a bimetallic brush adapted to engage the high portion of said cam as it rotates, means for adjusting the. relation between said brush and cam whereby the relation between its contacting and noncontacting travel can be varied, means for varying the speed of rotation of said cam, a thermostatically controlled motor circuit in which said cam circuit is interposed, and switch means for shunting across said cam circuit.

ERNEST o. WEBB. 

